The present invention relates to a machine for the spreading of fertilizers and seeds, in which, as viewed from the working direction, the structural width is greater than the structural length, and which can be assembled from at least two machine units, each of which is equipped with hoppers. Each of such machine units has a chassis borne at three support points by swivel wheels. Also, on the front transverse side in the working direction additional hitch elements are provided for hitching the machine units to a tractor for operation in the field, and in which the support points are at a relatively great distance apart. At least one wheel is in the form of a swivel wheel which can rotate 360.degree. about a vertical swivel axis.
A machine of this kind is disclosed in U.S. Pat. No. 3,884,309. This machine has the disadvantage that adjusting it between travel in the working direction and in the transport direction is extraordinarily difficult and time-consuming. This is because not just the swivel wheel but the other two wheels of each machine unit have to be locked in the working direction and in the transport direction, it being necessary, for the purpose of changing over from the one direction to the other, to use screw jacks to move the mounts of the wheels completely out of the mount guides. The machine in this case loses its stance, so that it would collapse if the machine units were not supported by other aids. Besides free space must be provided under the orientatable wheels, or else the changeover of the lockable wheels must be performed after the chassis has been removed.
A further disadvantage is that the machine cannot be supported uniformly on all wheels when assembled from the machine units, since the laterally disposed hitch elements of square cross section engage one another only in a telescoping manner. They do not permit any movement of the individual units in relation to one another. Particularly on the wavy ground surface so often encountered in practice, not to speak of even greater irregularities in the terrain, the entire weight of the machine is supported on the ground by only a few of the wheels at a time. This makes permanent twisting of the chassis unavoidable or even breakage in the long run. On this account, too, the uniform spreading of the material in the hoppers is impossible if the metering means of the machine units are driven by a wheel, since this wheel from time to time will be operating under insufficient loading, or may even be entirely suspended above the ground.
Furthermore, when the machine is hauled for long distances over the road, there is the disadvantage that on each machine unit two wheels located at a relatively great distance apart are locked. Consequently, on curves these wheels will scrape on the road surface. In addition to excessive tire wear, this can cause distortions or even breakage of the mounts of the locked up wheels if the roads and lanes are in poor condition.
A prospectus of the Versatile Company of Winnipeg-Manitoba, Canada discloses a chassis for a great number of harrow units, in which the above described disadvantages are overcome by constructing all eight road wheels as swivel wheels, three swivel wheels being able to be locked both in the working direction, and in the transport direction which is at right angles thereto. For the changeover for travel in the working direction, or for travel in the transport direction, only the one towbar needs to be attached to the tractor, the other towbar being raised to its transport position, and two swivel wheels situated one beside the other transversely to the direction of the travel need to be locked in position. To prevent any of the swivel wheels from becoming unloaded or from losing contact with the generally uneven ground surface thereby accordingly increasing the pressure on the other wheels, the frame of the unit is of torsionally flexible construction. Also, the harrow units, which in themselves are rigid, are attached to the chassis by chains. For the application for which the chassis is especially designed, that is, as a transportable chassis for harrow units, such a design is certainly advantageous. Nevertheless, this chassis is completely unsuited for the mounting of fertilizer spreaders and seeders, since the hoppers, the metering means and the broadcasters as well as the means whereby they are driven either cannot be constructed or disposed at all or only to a certain extent in a torsionally flexible manner.